Astronomy Day Three

Radiation, E-M Spectrum, Black Body Radiation, Doppler

Effect

Types of Ionizing Radiation

Alpha particles einstein

Beta particles

Gamma rays

neutron proton

e-

e- electron

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PENETRATING ABILITY

+ +

-

Paper

ALPHA

BETA

GAMA

WOOD

CONCRETE

SHIELDING

Light, a summary

1. Light travels at a speed of 300,000,000 meters per second

a. Any light traveling that is detected will be traveling at 3 x 108 meters per second

Light, a summary

1. Light travels at a speed of 300,000,000 meters per second

a. Any light traveling that is detected will be traveling at 3 x 108 meters per second.

b. This was calculated long before it was found experimentally.

Light, a summary

1. Light travels at a speed of 300,000,000 meters per second

a. Any light traveling that is detected will be traveling at 3 x 108 meters per second.

b. This was calculated long before it was found experimentally.

2. Light is a "ray", "wave", "radiation", "particle" and probably more than anything else, it is a disturbance in the fabric of space itself.

Light, a summary

1. Light travels at a speed of 300,000,000 meters per second

a. Any light traveling that is detected will be traveling at 3 x 108 meters per second.

b. This was calculated long before it was found experimentally.

2. Light is a "ray", "wave", "radiation", "particle" and probably more than anything else, it is a disturbance in the fabric of space itself.

a. A light wave has a wavelength, which is how long the wave is.

b. A light wave has a frequency, which is how many waves pass a certain point each second (Hz)

c. A light wave has a speed, which is always 3 x 108 meters per second.

d. The wavelength x frequency = velocity.

More energy will produce shorter wavelengths of light.

A "ray" of light is passing by. It has a 6.9 x 1014 Hz. What can we know about this light?

A "ray" of light is passing by. It has a 6.9 x 1014 Hz. What can we know about this light?

Speed?

Wavelength?

Location on E-M spectrum?

A "ray" of light is passing by. It has a 6.9 x 1014 Hz. What can we know about this light?

Speed? 3 x 108 meters per second. Always.

Wavelength? 3 x 108 = 6.9 x 1014 • wavelength,

So the wavelength = 3 x 108 ÷ 6.9 x 1014 , or 4.34 x 10-5 meters

Location on E-M spectrum? Visible. Blue.

KLIN radio (1,400 on your dial) has a frequency of 1,400,000 Hz. What is the wavelength of its signal?

The blackbody radiation curve will show the temperature of an object, based on where the peak of the curve is.

Our Sun has a temperature of about 6,000 K, why is that significant, based upon the location of the visible light area of the spectrum?

The Doppler effect is when the wavelength of an energy source is apparently changing, based upon the changing location of source or the observer.

The Doppler effect is when the wavelength or speed of an energy source is apparently changing, based upon the changing location of source or the observer.

45 mph

Sound of engine will seem lower

Sound of engine will seem higher

Show Doppler effect animation here

http://www.lon-capa.org/~mmp/applist/doppler/d.htm

Airplane is flying at 400 m/s, and bullet shoots ahead at 400 m/s. What is the speed and direction of the bullet?

Airplane is flying at 400 m/s, and bullet shoots ahead at 400 m/s. What is the speed and direction of the bullet?

Straight ahead at 800 meters per second.

Both airplanes are flying at 400 m/s, and the lead airplane shoots straight back, with a bullet that has a speed of 400 m/s. What is the speed and direction of the bullet?

Both airplanes are flying at 400 m/s, and the lead airplane shoots straight back, with a bullet that has a speed of 400 m/s. What is the speed and direction of the bullet?

It will have a ground velocity of zero. It will fall straight down.

Both airplanes are flying at 400 m/s. Will the sound of plane "a" be higher, lower, or the same as plane "b", to the pilot of plane "b"?

a b

Both airplanes are flying at 400 m/s. Will the sound of plane "a" be higher, lower, or the same as plane "b", to the person on the ground?

a b

Both airplanes are flying at 400 m/s. Will the sound of plane "a" be higher, lower, or the same as plane "b", to the person on the ground?

"a" will be higher, "b" will be lower.

a b

a b

Spaceship "b" shoots a "photon torpedo" at "a". What will be the speed of the "photon torpedo" when it reaches "a"?

Speed is 1/4 cSpeed is 0 c

a b

Spaceship "b" shoots a "photon torpedo" at "a". What will be the speed of the "photon torpedo" when it reaches "a"?

Speed is 1/4 cSpeed is 0 c

It MUST be 300,000,000 meters per second. ALWAYS

a b

Speed is 1/4 cSpeed is 1/4 c

Both spacecraft are moving at great velocity from left to right.

1. Which will appear "blueshifted" to Albert?

2. Which will appear "redshifted" to Albert?

3. What color do they appear to each other?

a b

Speed is 1/4 cSpeed is 1/4 c

Both spacecraft are moving at great velocity from left to right.

1. Which will appear "blueshifted" to Albert? "a"

2. Which will appear "redshifted" to Albert? "b"

3. What color do they appear to each other? Still green.

Self-Test: True or False, on page 80

1-15, just the evens

Self-Test: Fill in the blank, on page 80

1-15, just the odds

AND THEN DO ONE OF THE FOLOWING

Problems on page 81

Problems 1 and 2

OR

Collaborative Exercise

Exercise one on page 82

1. Light, radio, ultraviolet and gamma rays are all forms of _________

2. Sound waves cannot travel through space, but electromagnetic waves can, because space is a _____________

3. All electromagnetic waves travel at _________________________ m/s

4. The waves with the shortest wavelengths are _________________________ and the longest types of waves are the ___________________________.

5. A perfect blackbody will release (less)(same)(more) radiation than it (makes)(reflects)(absorbs).

6. The frequency of blackbody radiation is related to ______________________.

7. Objects moving away form an observer appear to be more ________ in color, while object coming towards an observer appear to be more_____ in color.

8. A radio wave is (faster)(slower)(same) as the speed of a gamma ray.

9. The ___________________ is the distance between two wave crests.

10. When a charged particle moves through space, information about this motion is transmitted by means of its changing ____________ and ___________ fields.

11. Light with a wavelength of 700 nm is perceived to be __________________ in color.

12. A word that means something cannot be seen through is ___________________.

13. The lowest possible temperature is _______K. Water boils at _________K, at standard atmospheric pressure.

14. Because the Sun emits its peak amount of radiation at about 480 nm, its temperature must be about _______K.

15. Something is emitting X-rays. Its temperature is very (low)(cool)(hot)(smokin’)

16. What is so special about “c”?

17. What is the speed of a wave, moving through water, with a frequency of 256 Hz, and a wavelength of 5.77 meters?

18. KLIN radio broadcasts at a frequency of 1,400,000 Hz. How long are the radio waves?

1. Light, radio, ultraviolet and gamma rays are all forms of ELECTROMAGNETIC RADIATION

2. Sound waves cannot travel through space, but electromagnetic waves can, because space is a VACUUM

3. All electromagnetic waves travel at 3.0 X 108 m/s

4. The waves with the shortest wavelengths are _GAMMA__ and the longest types of waves are the _RADIO WAVES_.

5. A perfect blackbody will release (less)(SAME)(more) radiation than it (makes)(reflects)(ABSORBS).

6. The frequency of blackbody radiation is related to _TEMPERATURE__.

7. Objects moving away form an observer appear to be more _RED_ in color, while object coming towards an observer appear to be more_BLUE_ in color.

8. A radio wave is (faster)(slower)(SAME) as the speed of a gamma ray.

9. The _WAVELENGTH_ is the distance between two wave crests.

10. When a charged particle moves through space, information about this motion is transmitted by means of its changing ELECTRIC and MAGNETIC fields.

11. Light with a wavelength of 700 nm is perceived to be _RED_ in color.

12. A word that means something cannot be seen through is _OPAQUE__.

13. The lowest possible temperature is _0K____. Water boils at _373 K, at standard atmospheric pressure.

14. Because the Sun emits its peak amount of radiation at about 480 nm, its temperature must be about 6,000 K.

15. Something is emitting X-rays. Its temperature is very (low)(cool)(HOT)(smokin’)

16. What is so special about “c”? THIS IS THE UNCHANGING SPEED OF LIGHT

17. What is the speed of a wave, moving through water, with a frequency of 256.0 Hz, and a wavelength of 5.77 meters?

256.0 X 5.77 = 1,477.12 m/s

18. KLIN radio broadcasts at a frequency of 1,400,000 Hz. How long are the radio waves?

300,000,000 ÷1,400,000 Hz = 214.3 meters

Page 80 True and False (evens)

2. False, sound is not electromagnetic

4. False, interference is when crests and troughs collide

6. True. They all travel a 300,000 kilometers per second

8. False. Gamma radiation has the shortest wavelength of all

10. True. The exact amount of radiation that goes in will also come out

12. True. The higher the temperature, the higher the frequency

14. True. Doppler works for everything that is a wave.

Page 80 Fill in Blank (Odds)

1. 300,000 kilometers per second, or 300,000,000 meters per second

3. Frequency

5 Electrical and Magnetic

7. 700 nm would be red

9. Heat

11. 273 Kelvin (not degrees)

13. The object that is 1,200 K will emit twice as much energy as an object that is 1,000 K

15. Blue

1.

Wavelength is 5.77 meters

Frequency is 256 cycles per second

Speed is 5.77 x 256 = 1,480 meters per second

2.

Frequency is 100 MHz , or 1 x 108 / second

Velocity is 3 x 108 meters/second

Wavelength is ( 3 x 108 meters/second)÷(1 x 108 / second) = 3 meters